The black Kay Unger dress was perfect for two reasons. First, it was gorgeous. (Feldstein revealed it actually fit her better now than it did in high school.)

And secondly, it was a subtle tribute to the cast (and fans) of “Lady Bird,” in which Feldstein plays Julie, an uncool high school student and loyal best friend.

“I love how my character’s story ends at the prom, so like, for the first time I’m going to an awards show as a nominee with the cast, it’s like, 'You gotta wear your prom dress, girl, and honor Julie,'" she told The Cut.

Feldstein and her fellow "Lady Bird" cast members were nominated for outstanding performance by a cast in a motion picture. Her co-star and off-screen friend Saoirse Ronan was nominated for best performance by a leading female actor.

Feldstein, whose older brother is the actor Jonah Hill, is a relatively new face to the awards circuit.

Before "Lady Bird," she appeared alongside Seth Rogen and Zac Efron in the comedy “Neighbors 2: Sorority Rising." On Broadway, she shared the stage with Bette Midler and David Hyde Pierce in “Hello, Dolly!”